Problem: Which of these numbers is composite? ${13,\ 17,\ 29,\ 64,\ 67}$
Solution: A composite number is a number that has more than two factors (including 1 and itself). 13, 17, 29, and 67 each have only two factors. The factors of 64 are 1, 2, 4, 8, 16, 32, and 64. Thus, 64 is the composite number.